We propose to carry out research on the structure and function of biological membranes: 1) to investigate the molecular explanation for the low solubility of amphipathic molecules in real membranes which we have recently discovered; 2) to investigate the molecular mechanisms involved in the capping of membrane receptors by lectins and antibodies, in both erythroid and non-erythroid cells; 3) to explore the proposal that the in vivo maturation of reticulocytes to mature erythrocytes involves the pinching off of small regions of the reticulocyte membrane devoid of spectrin during circulation of the reticulocytes through the reticuloendothelial system; 4) to explore the molecular mechanisms in cytotoxic T lymphocyte killing of virus-infected autologous and syngeneic target cells.